Power distribution device

ABSTRACT

A power distribution device includes a first switch configured to connect a power supply source or a first device to a second device, a second switch configured to connect the second device and a third device distributing predetermined power, and a control unit configured to control conduction and cutoff of the first and the second switches based on an output voltage of the power distribution device. The control unit switches the first switch to a conductive state and the second switch to a cutoff state when an input voltage of the second device does not drop to a predetermined control start voltage, and switches, when the input voltage of the second device temporarily drops to the control start voltage, the first switch to the cutoff state and the second switch to the conductive state, and supplies the power from the third device to the second device.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.16/878,712 filed May 20, 2020, which is based on and claims priorityunder 35 U.S.C. 119 from Japanese Patent Application No. 2019-143825filed on Aug. 5, 2019, incorporated herein by reference in its entirety.

BACKGROUND 1. Technical Field

The disclosure relates to a power distribution device that distributespower of a power supply source to a plurality of devices.

2. Description of Related Art

In a vehicle, it is necessary to appropriately supply power from a powersupply source, such as a generator and a battery, to a plurality ofin-vehicle devices. In general, power is supplied by connecting thepower supply source and each of the in-vehicle devices using a wireharness, which is an assembly of a large number of electric wires.However, in recent years, the number of in-vehicle devices has beenincreasing, and thus wiring structures of power supply lines andcommunication lines in a vehicle are too complicated.

To address this problem, JP-A-2017-019328 proposes a power distributionstructure in which a power supply of a vehicle is constructed as a mainline routed inside the vehicle, power supply boxes are provided atvarious points on the main line, and each in-vehicle device is suppliedpower from the nearest power supply box.

SUMMARY

However, according to the disclosure described in JP-A-2017-019328,since a plurality of power supply boxes are connected in a treestructure, when the output voltage of the upstream power supply box isunstable due to, for example, temporary large current consumption, powersupply to the downstream power supply box connected to the power supplybox will be affected.

The present disclosure is intended to address such a shortcoming, ofwhich an objective is to provide a power distribution device which canreduce influence on the power supplied to a power supply box connectedat a downstream side even when an output voltage of an upstream powersupply box is unstable.

In order to address the shortcoming stated above, one aspect of thepresent disclosure is to provide a power distribution device that isdirectly connected to a power supply source mounted on a vehicle orindirectly connected to the power supply source via a first device, anddistributes power of the power supply source to a second device. Thepower distribution device includes: a first switch configured to connectthe power supply source or the first device to the second device; asecond switch configured to connect the second device and a third devicecapable of distributing predetermined power; and a control unitconfigured to control conduction and cutoff of the first switch and thesecond switch based on an output voltage of the power distributiondevice. The control unit is configured to: switch the first switch to aconductive state and the second switch to a cutoff state if an inputvoltage of the second device does not drop to a predetermined controlstart voltage; and switch, when the input voltage of the second devicetemporarily drops to the control start voltage, the first switch to thecutoff state and second switch to the conductive state, and control thethird device such that the third device supplies power to the seconddevice.

With the power distribution device according to the present disclosure,when the output voltage to a downstream device (second device) to whichthe power of the power supply source is supplied is unstable, theinfluence on the power supply to the downstream device can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance ofexemplary embodiments of the disclosure will be described below withreference to the accompanying drawings, in which like signs denote likeelements, and wherein:

FIG. 1 is a schematic configuration diagram of a power supply systemincluding a power distribution device according to a first embodiment;

FIG. 2 is a detailed view of the power distribution device according tothe first embodiment;

FIG. 3 is an exemplified timing chart of switching control executed bythe power distribution device according to the first embodiment;

FIG. 4A is a diagram illustrating a power supply path when each switchis switched to a first state;

FIG. 4B is a diagram illustrating a power supply path when each switchis switched to a second state;

FIG. 5 is a schematic configuration diagram of a power supply systemincluding a power distribution device according to a second embodiment;

FIG. 6 is a detailed view of the power distribution device according tothe second embodiment;

FIG. 7 is an exemplified timing chart of switching control executed bythe power distribution device according to the second embodiment; and

FIG. 8 is a schematic configuration diagram of a power supply systemincluding a power distribution device according to an applicationexample.

DETAILED DESCRIPTION OF EMBODIMENTS

The power distribution device of the present disclosure stops the powersupply from the original power distribution device to a downstreamdevice when an output voltage for the downstream device to which thepower is supplied is unstable. The downstream device is connected toanother power distribution device and is supplied power from the otherpower distribution device. Consequently, the influence on the powersupply to the downstream device can be reduced.

Hereinafter, the power distribution device according to embodiments ofthe present disclosure will be described in detail with reference to thedrawings.

First Embodiment

Configuration

FIG. 1 is a diagram illustrating a schematic configuration example of apower supply system including a power distribution device according to afirst embodiment of the present disclosure. A power supply system 1according to the present embodiment illustrated in FIG. 1 includes apower supply source 10, a relay box (R/B) 20, and a plurality of powerdistribution devices 31, 32, 33 and 34. The power supply system 1 may bemounted on, for example, a vehicle, and is configured to be able tosupply power of the power supply source 10 to a plurality of in-vehicledevices 41, 42, 43, and 44 which are electric loads.

The power supply source 10 is a power supply device capable of supplyingpower, and examples thereof include a generator 11 such as analternator, and a battery 12 that is a power storage element such as anauxiliary battery. Further, the power supply source 10 may include aDC-DC converter that converts power of a driving battery into power of apredetermined voltage, and outputs the power.

A relay box 20 is an embodiment of a power supply box that candistribute power supplied from the power supply source 10 to apredetermined number of loads. The relay box 20 of the presentembodiment divides the power supplied from the power supply source 10into two, and outputs a first portion of power to a power distributiondevice A_31, and a second portion of power to a power distributiondevice B_32. The power supply source 10 may be directly connected to thepower distribution device A_31 and the power distribution device B_32without using the relay box 20.

The power distribution device A_31 is the power distribution deviceaccording to the first embodiment, and one aspect of the power supplybox capable of distributing the first portion of power output from therelay box 20 for a plurality of loads, and of switching a powerdistribution destination in accordance with a current consumption statusof an in-vehicle device a_41. The power distribution device A_31includes a switch SW1, a switch SW2, and a control unit C1 asillustrated in the detailed view of FIG. 2.

The switch SW1 is inserted between an input terminal to which the relaybox 20 is connected and an output terminal to which a power distributiondevice C_33 is connected. The switch SW2 is inserted between the outputterminal and a switch SW3 (described later) of the power distributiondevice B_32. The in-vehicle device a_41 is connected to a pathconnecting the input terminal and the switch SW1. The control unit C1can detect an input current I1 flowing into the input terminal, anoutput current I2 flowing out of the output terminal, an input voltageV1 at the input terminal, and an output voltage V2 at the outputterminal, respectively. Then, the control unit C1 controls conductionand cutoff of the switches SW1 and SW2 based on the input current I1,the output current I2, the input voltage V1, and the output voltage V2,which have been detected. Further, the control unit C1 is communicablyconnected to a control unit C2 (described later) of the powerdistribution device B_32.

In the example of FIG. 2, the power distribution device A_31 distributesthe first portion of power output from the relay box 20 for a pluralityof loads, supplies a portion of the first portion of power to thein-vehicle device a_41, and supplies a portion of the first portion ofpower to the control unit C1. Then, in a case where the switch SW1 is ina conductive state by the control of the control unit C1, the remainingpower is output to the power distribution device C_33 via the switchSW1. The control of the control unit C1 will be described later.

The power distribution device B_32 is the power distribution deviceaccording to the first embodiment, and one aspect of the power supplybox capable of distributing the second portion of power output from therelay box 20 for a plurality of loads, and of switching a powerdistribution destination in accordance with a current consumption statusof an in-vehicle device b_42. The power distribution device B_32includes a switch SW3, a switch SW4, and a control unit C2 asillustrated in the detailed diagram of FIG. 2, and has a symmetricconfiguration with that of the power distribution device A_31.

The switch SW4 is inserted between the input terminal to which the relaybox 20 is connected and the output terminal to which a powerdistribution device D_34 is connected. The switch SW3 is insertedbetween the output terminal and the switch SW2 of the power distributiondevice A_31. The in-vehicle device b_42 is connected to a pathconnecting the input terminal and the switch SW4. The control unit C2can detect an input current I4 flowing into the input terminal, anoutput current I3 flowing out of the output terminal, an input voltageV4 at the input terminal, and an output voltage V3 at the outputterminal, respectively. Then, the control unit C2 controls conductionand cutoff of the switches SW4 and SW3 based on the input current I4,the output current I3, the input voltage V4, and the output voltage V3,which have been detected. Further, the control unit C2 is communicablyconnected to the control unit C1 of the power distribution device A_31.

In the example of FIG. 2, the power distribution device B_32 distributesthe second portion of power output from the relay box 20 for a pluralityof loads, supplies a portion of the second portion of power to thein-vehicle device b_42, and supplies a portion of the second portion ofpower to the control unit C2. Then, in a case where the switch SW4 is ina conductive state by the control of the control unit C2, the remainingpower is output to the power distribution device D_34 via the switchSW4. Since the control of the control unit C2 is the same as that of thecontrol unit C1, description will be omitted except for the descriptionof the control unit C1.

The power distribution device C_33 is one aspect of the power supplybox, and can distribute the power output from the power distributiondevice A_31 for a plurality of loads, and supply one component of thepower to an in-vehicle device c_43 as a power source, as illustrated inthe detailed view of FIG. 2.

The power distribution device D_34 is one aspect of the power supplybox, and can distribute the power output from the power distributiondevice B_32 for a plurality of loads, and supply one component of thepower to an in-vehicle device d_44 as a power source, as illustrated inthe detailed view of FIG. 2.

Although FIGS. 1 and 2 show an example in which four power distributiondevices 31, 32, 33, and 34 are connected in a π-type tree structure, thenumber of, and connection structure of, the power distribution devicesare not limited thereto. Basically, the power distribution device, towhich a power distribution device to be supplied power is connected at adownstream side, has a configuration which is the same as that of thepower distribution device A_31 or the power distribution device B_32. Apower distribution device at the end of the π-type tree structure, towhich no power distribution device to be supplied power is connected atthe downstream side, has a configuration which is the same as that ofthe power distribution device C_33 or the power distribution deviceD_34. Further, the in-vehicle devices 41, 42, 43, and 44 connected tothe power distribution devices 31, 32, 33, and 34 are not limited to thedevices shown in FIGS. 1 and 2. Further, the switches SW1, SW2, SW3, andSW4 are exemplified by switches using semiconductor elements, but may beswitches of mechanical relays. Further, the control units C1 and C2 maybe configured as electronic control units (ECU) respectively including aprocessor, a memory, and an input/output interface. Further, a flatwiring member (bus bar) through which a large current can flow can beused for power lines connecting the power distribution devices.

Control

Next, the control executed by the power distribution device according tothe first embodiment of the present disclosure will be described withreference to FIGS. 3, 4A, and 4B. FIG. 3 is a timing chart illustratingswitching control executed by the power distribution devices A_31 andB_32 in a case where large current consumption occurs in the in-vehicledevice a_41, as an example. In this example, it is assumed that aconsumption current of the in-vehicle device c_43 is constant during aswitching period, and that the power distribution device B_32 has enoughpower to sufficiently supply the consumption current of the in-vehicledevice c_43.

In a case where time<t1, the current consumption of each in-vehicledevice falls within a predetermined range, and conduction (ON) andcutoff (OFF) states of each switch correspond to a first state in whichnormal power supply is performed (SW1: ON, SW2: OFF, SW3: OFF, and SW4:ON). FIG. 4A illustrates a power supply path in the first state. In FIG.3, the input voltage of the power distribution device C_33 falls belowthe input voltage V1 of the power distribution device A_31 by a voltagedrop obtained from the output current I2 of the power distributiondevice A_31 and a resistance (wiring resistance R) of the wire harnessconnecting the power distribution device A_31 and the power distributiondevice C_33 (the voltage drop at the switch SW1 is negligible).

In a case were t1≤time<t2, the input voltage V1 (=output voltage V2) ofthe power distribution device A_31 gradually decreases in accordancewith the large current consumption occurring in the in-vehicle devicea_41, and accordingly, the input voltage of the power distributiondevice C_33 also gradually decreases. The input voltage V1 decreasesbased on the wiring resistance of the wire harness connecting the relaybox 20 and the power distribution device A_31 and the consumptioncurrent of the in-vehicle device a_41.

In a case where time=t2, since the input voltage of the powerdistribution device C_33 decreases to a control start voltage, thecontrol unit C1 of the power distribution device A_31 executes theswitching. At the time t2, the switch SW2 and the switch SW3 are firstturned on (SW1: ON, SW2: ON, SW3: ON and SW4: ON) so that the powersupply to the power distribution device C_33 does not stop when theswitches are switched. Accordingly, the power can be supplied to thepower distribution device C_33 from either the power distribution deviceA_31 or the power distribution device B_32. The control unit C1estimates that the input voltage of the power distribution device C_33decreases to the control start voltage from the output current I2, theoutput voltage V2, and the wiring resistance R. The control startvoltage is set to be equal to or higher than the minimum voltagerequired for stably operating the in-vehicle device c_43.

In a case where time=t3, the control unit C1 of the power distributiondevice A_31 cuts off the switch SW1 to set the switch SW1 to the secondstate after a predetermined time has elapsed (SW1: OFF, SW2: ON, SW3: ONand SW4: ON). FIG. 4B illustrates a power supply path in the secondstate. Consequently, the input terminal and the output terminal of thepower distribution device A_31 are disconnected, and the output voltageV2 is not influenced by the large current consumption in the in-vehicledevice a_41. The output voltage V3 of the power distribution device B_32is applied to the output voltage V2 of the power distribution deviceA_31 via the switches SW2 and SW3.

In a case where t3<time<t4, since the large current consumption in thein-vehicle device a_41 continues, the input voltage V1 of the powerdistribution device A_31 continues to decrease. On the other hand, theinput voltage of the power distribution device C_33 (that is, the outputvoltage V2 of the power distribution device A_31) gradually increaseswhile being influenced by the current consumption in the in-vehicledevices b_42 and d_44. For comparison, the input voltage of the powerdistribution device C_33 when the switching control is not performed isindicated by a dashed line in FIG. 3.

In a case where t4≤time<t5, the large current consumption in thein-vehicle device a_41 is ceased, and the input voltage V1 of the powerdistribution device A_31 starts to increase. The input voltage of thepower distribution device C_33 (that is, the output voltage V2 of thepower distribution device A_31) also gradually increases based on thecurrent consumption of the in-vehicle devices b_42 and d_44.

In a case where time=t5, since the input voltage V1 of the powerdistribution device A_31 has increased to the control end voltage, thecontrol unit C1 of the power distribution device A_31 cancels theswitching, i.e. returns the second state to the first state. The switchSW1 is first turned on (SW1: ON, SW2: ON, SW3: ON and SW4: ON) so thatthe power supply to the power distribution device C_33 does not stopeven when the switching is canceled. Accordingly, the input terminal andthe output terminal of the power distribution device A_31 are connected,and then power can be supplied to the power distribution device C_33from either the power distribution device A_31 or the power distributiondevice B_32. Further, the control end voltage is set to a voltage atwhich the input voltage of the power distribution device C_33 does notimmediately drop to the control start voltage due to the consumptioncurrent of the in-vehicle device c_43 when returning to the first state.

In a case where time=t6, the control unit C1 of the power distributiondevice A_31 cuts off the switches SW2 and the SW3 to set them to thefirst state after a predetermined time has elapsed (SW1: ON, SW2: OFF,SW3: OFF and SW4: ON). Consequently, the power distribution device B_32is disconnected from the power distribution device A_31, and power issupplied from only the power distribution device A_31 to the powerdistribution device C_33 (see FIG. 4A).

Action & Effect

As stated above, according to the power distribution device of the firstembodiment, the power distribution device of the present disclosurestops the power supply from the power distribution device to adownstream device when an output voltage for the downstream device towhich the power is supplied is unstable due to temporary large currentconsumption of the in-vehicle devices connected thereto. The downstreamdevice is connected to the other power distribution device and issupplied power from the original other power distribution device.Consequently, the influence on the power supply to the downstream devicecan be reduced in a case where the output voltage to the downstreamdevice is unstable.

Further, according to the power distribution device of the firstembodiment, the power distribution device cuts off the path forsupplying power from the other power distribution device to thedownstream device when the output voltage for the downstream device towhich the power is supplied is no longer unstable, and when the path forsupplying the power from the original power distribution device to thedownstream device becomes conductive. Accordingly, the power supplysystem can be returned to the normal power supply state.

Second Embodiment

Configuration

FIG. 5 is a diagram illustrating a schematic configuration example of apower supply system including a power distribution device according to asecond embodiment of the present disclosure. A power supply system 2according to the present embodiment illustrated in FIG. 5 includes thepower supply source 10, the relay box (R/B) 20, a plurality of powerdistribution devices 51, 52, 53 and 54, and a detector 60 according tothe second embodiment. The power supply system 2 may be mounted on, forexample, a vehicle, and is configured to be able to supply power of thepower supply source 10 to a plurality of in-vehicle devices 41, 42, 43,and 44 which are electric loads.

The power supply system 2 according to the second embodiment is the sameas the power supply system 1 according to the first embodiment exceptthat the former has a plurality of power distribution devices 51, 52,53, and 54, and the detector 60. Hereinafter, the second embodiment willbe described focusing on these different configurations, and parts ofthe configuration having the same reference numerals will not bedescribed.

A power distribution device A_51 is one aspect of the power supply boxcapable of distributing the first portion of power output from the relaybox 20 for a plurality of loads, and of switching a power distributionstatus. The power distribution device A_51 includes a switch SW11, aswitch SW12, and a control unit C11 as illustrated in the detailed viewof FIG. 6.

The switch SW11 is inserted between an input terminal to which the relaybox 20 is connected and an output terminal to which a power distributiondevice C_53 is connected. The switch SW12 is inserted between the inputterminal and a switch SW13 (described later) of a power distributiondevice B_52. The in-vehicle device a_41 is connected to the inputterminal. The control unit C11 can receive a collision signal outputfrom the detector 60 described later. Then, the control unit C11controls conduction and cutoff of the switches SW11 and SW12 based onthe received collision signal.

In the example of FIG. 6, the power distribution device A_51 distributesthe first portion of power output from the relay box 20 for a pluralityof loads, supplies a portion of the first portion of power to thein-vehicle device a_41, and supplies a portion of the first portion ofpower to the control unit C11. Then, in a case where the switch SW11 isin a conductive state by the control of the control unit C11, theremaining power is output to the power distribution device C_53 via theswitch SW11. The control of the control unit C11 will be describedlater.

The power distribution device B_52 is one aspect of the power supply boxcapable of distributing the second portion of power output from therelay box 20 for a plurality of loads, and of switching a powerdistribution status. The power distribution device B_52 includes aswitch SW13, a switch SW14, and a control unit C12 as illustrated in thedetailed view of FIG. 6.

The switch SW14 is inserted between the input terminal to which therelay box 20 is connected and the output terminal to which a powerdistribution device D_54 is connected. The switch SW13 is insertedbetween the input terminal and the switch SW12 of the power distributiondevice A_51. The in-vehicle device b_42 is connected to the inputterminal. The control unit C12 can receive the collision signal outputfrom the detector 60 described later. Then, the control unit C12controls conduction and cutoff of the switches SW13 and SW14 based onthe received collision signal.

In the example of FIG. 6, the power distribution device B_52 distributesthe second portion of power output from the relay box 20 for a pluralityof loads, supplies a portion of the second portion of power to thein-vehicle device b_42, and supplies a portion of the second portion ofpower to the control unit C12. Then, in a case where the switch SW14 isin a conductive state by the control of the control unit C12, theremaining power is output to the power distribution device D_54 via theswitch SW14. Since the control of the control unit C12 is the same asthat of the control unit C11, description will be omitted except for thedescription of the control unit C11.

The power distribution device C_53 is one aspect of the power supply boxcapable of distributing the power output from the power distributiondevice A_51 for a plurality of loads, and of switching a powerdistribution status. The power distribution device C_53 includes aswitch SW15, a switch SW16, and a control unit C13 as illustrated in thedetailed view of FIG. 6.

The switch SW15 is inserted between the input terminal to which thepower distribution device A_51 is connected and the output terminal towhich the in-vehicle device c_43 is connected. The switch SW16 isinserted between the output terminal and a switch SW17 (described later)of the power distribution device D_54. The control unit C13 can receivethe collision signal output from the detector 60 described later. Then,the control unit C13 controls conduction and cutoff of the switches SW15and SW16 based on the received collision signal.

In the example of FIG. 6, the power distribution device C_53 distributesthe power output from the power distribution device A_51 for a pluralityof loads, and supplies a portion of the power to the in-vehicle devicec_43 via the switch SW15 in a case where the switch SW15 is in aconductive state by the control of the control unit C13. The remainingpower is supplied to the control unit C13 as a power source.

The power distribution device D_54 is one aspect of the power supply boxcapable of distributing the power output from the power distributiondevice B_52 for a plurality of loads, and of switching a powerdistribution status. The power distribution device D_54 includes aswitch SW17, a switch SW18, and a control unit C14 as illustrated in thedetailed view of FIG. 6.

The switch SW18 is inserted between the input terminal to which thepower distribution device B_52 is connected and the output terminal towhich the in-vehicle device d_44 is connected. The switch SW17 isinserted between the output terminal and the switch SW16 of the powerdistribution device C_53. The control unit C14 can receive the collisionsignal output from the detector 60 described later. Then, the controlunit C14 controls conduction and cutoff of the switches SW17 and SW18based on the received collision signal.

In the example of FIG. 6, the power distribution device D_54 distributesthe power output from the power distribution device B_52 for a pluralityof loads, and supplies a portion of the power to the in-vehicle deviced_44 via the switch SW18 in a case where the switch SW18 is in aconductive state by the control of the control unit C14. The remainingpower is supplied to the control unit C14 as a power source.

Although FIGS. 5 and 6 show an example in which four power distributiondevices 51, 52, 53, and 54 are connected in a round structure, thenumber of, and connection structure of, the power distribution devicesare not limited thereto. Basically, there is no limitation as long as aconfiguration in which the power distribution devices are connected toeach other via respective switches is adopted. Further, the in-vehicledevices 41, 42, 43, and 44 connected to the power distribution devices31, 32, 33, and 34 are not limited to the devices shown in FIGS. 5 and6. Further, the switches SW11, SW12, SW13, SW14, SW15, SW16, SW17 andSW18 are exemplified by switches using semiconductor elements, but maybe switches of mechanical relays. Further, the control units C11, C12,C13 and C14 may be configured as ECUs respectively including aprocessor, a memory, and an input/output interface. Further, a flatwiring member (bus bar) through which a large current can flow can beused for power lines connecting the power distribution devices.

The detector 60 is a device capable of determining that the vehicle hasbeen involved in a collision and of specifying a location of the vehiclewhere the collision has occurred with certainty. For example, thedetector 60 may include an airbag ECU, a collision sensor and anacceleration sensor. The detector 60 specifies a power supply wiringpath that is likely to be damaged by the collision of the vehicle basedon whether an inflator is operated or not, a detected position of thesensor, and a magnitude and time of an input acceleration, and outputsthe collision signal indicating the specified power supply wiring pathto the power distribution devices 51, 52, 53, and 54.

Control

Next, the control executed by the power distribution device according tothe second embodiment of the present disclosure will be described withreference to FIG. 7 FIG. 7 is a timing chart illustrating the switchingcontrol in a case where the collision signal is output from the detector60 to each power distribution device, wherein the collision signalincludes information indicating that the power supply wiring pathbetween the power distribution device A_51 and the power distributiondevice C_53 is likely to be damaged (A-C: X). In this example, it isassumed that all the switches are normally in the conductive state.

The power distribution device A_51 that has received the collisionsignal cuts off the switch SW11 inserted between the power distributiondevice A_51 and the power distribution device C_53 (SW11: OFF). Further,the power distribution device C_53 that has received the collisionsignal cuts off the switch SW15 inserted between the power distributiondevice A_51 and the power distribution device C_53 (SW15: OFF). Withthis switching control, the output terminal of the power distributiondevice A_51 and the input terminal of the power distribution device C_53are disconnected.

Further, in order to avoid interruption of the power supply wiring dueto an erroneous determination of the detector 60, for example, in a casewhere the collision signal in the form of a pulse is output due to theinfluence of noise, the collision signal is received from the detector60, and then the switches SW11 and SW15 may be cut off after waiting fora predetermined time T as shown in FIG. 7. In this case, thepredetermined time T is required to be set so as to not allow theoccurrence of a specific event such as smoking even when the detector 60makes an accurate determination, not an erroneous determination.

It is assumed that all the switches are in the conductive state as anormal state in which the collision signal is not received. However, theswitches SW16 and SW17 connecting the power distribution device C_53 andthe power distribution device D_54 may be in the cutoff state. In thiscase, after the control units C13 and C14 receive the collision signalindicating the power supply wiring path between the power distributiondevice A_51 and the power distribution device C_53, or alternatively,the power supply wiring path between the power distribution device B_52and the power distribution device D_54, from the detector 60, theswitches SW16 and SW17 may be switched to the conductive state,respectively.

Action & Effect

As described above, according to the power distribution device accordingto the second embodiment, when it is determined that it is likely thatthe power supply wiring is damaged due to a collision of the vehicle orthe like, the power supply wiring is cut off before and after a pointwhere the collision has occurred so as to be disconnected. Thus, whenabnormalities such as ground fault occur due to the impact of thecollision, it is possible to avoid a situation where the power supplyfails.

Application Example

By adopting a configuration of the application example shown in FIG. 8,it is possible to control both the switching control for switching tothe power supply path to the downstream device when the output voltageto the downstream device is unstable, as described in the firstembodiment, and the switching control for disconnecting a point wherethe power supply wiring is likely to be damaged due to a collision ofthe vehicle, as described in the second embodiment.

The present disclosure relates to not only the power supply systemincluding the power distribution device, but also to a vehicle equippedwith the power supply system including the power distribution device.

The power distribution device of the present disclosure can be used forvehicles such as automobiles.

What is claimed is:
 1. A power distribution device that is directlyconnected to a power supply source mounted on a vehicle or indirectlyconnected to the power supply source via a first device and distributespower of the power supply source to a second device, the powerdistribution device comprising: a first switch configured to connect thepower supply source or the first device to the second device; a secondswitch configured to connect the second device to a third deviceconfigured to distribute predetermined power; and a control unitconfigured to control conduction and cutoff of the first switch and thesecond switch based on an output voltage of the power distributiondevice, wherein the control unit is configured to switch, when the inputvoltage of the second device temporarily drops to the control startvoltage, the first switch to the cutoff state and the second switch tothe conductive state, and control the third device such that the thirddevice supplies power to the second device.
 2. The power distributiondevice according to claim 1, wherein the input voltage of the seconddevice is obtained based on the output voltage and an output current ofthe power distribution device, and a wiring resistance from the powerdistribution device to the second device.
 3. The power distributiondevice according to claim 1, wherein the control unit is configured toswitch, when the input voltage of the second device becomes equal to orlower than the control start voltage and then an input voltage of thepower distribution device becomes equal to or higher than apredetermined control end voltage, the first switch to the conductivestate and the second switch to the cutoff state.
 4. The powerdistribution device according to claim 3, wherein the control endvoltage is set to a value such that the input voltage of the seconddevice does not fall below the control start voltage immediately afterthe control unit determines that the input voltage of the second devicehas become equal to or lower than the control end voltage and switchesthe first switch to the conductive state and the second switch to thecutoff state.
 5. The power distribution device according to claim 1,wherein the control unit is configured to switch, when the input voltageof the second device temporarily drops to the control start voltage, thesecond switch to the conductive state, and then the first switch to thecutoff state after a predetermined time has elapsed.
 6. The powerdistribution device according to claim 3, wherein the control unit isconfigured to switch, when the input voltage of the second devicebecomes equal to or lower than the control start voltage and then theinput voltage of the power distribution device becomes equal to orhigher than the control end voltage, the first switch to the conductivestate, and then the second switch to the cutoff state after apredetermined time has elapsed.
 7. A power distribution device that isdirectly connected to a power supply source mounted on a vehicle orindirectly connected to the power supply source via a first device, anddistributes power of the power supply source to a second device, thepower distribution device comprising: a first switch configured toconnect the power supply source or the first device to the seconddevice; a second switch configured to connect the second device to athird device configured to distribute predetermined power; and a controlunit configured to control conduction and cutoff of the first switch andthe second switch based on a collision signal indicating a wiring pathlikely to be damaged by a collision of a vehicle, the collision signalbeing received from a predetermined detector, wherein the control unitis configured to switch the first switch to a cutoff state and thesecond switch to the conductive state when receiving the collisionsignal indicating a wiring path from the power distribution device tothe second device.
 8. The power distribution device according to claim7, wherein the predetermined detector is configured to specify thewiring path likely to be damaged by the collision of the vehicle basedon information on a detection state of a sensor, an operation state ofan airbag, an input acceleration and a time, which is obtained from thevehicle.